Drawing metal



Patented Dec. 7, 1943 UNITED STATES PATENT OFFICE DRAWING METAL John L.Goheen, Jr., and Charles F. Catlin, Jr.,

Huntington, W. Va., assignors to The International Nickel Company, Inc.,New York, N. Y.', a corporation of Delaware I No Drawing; ApplicationJuly 27, 1942 Serial No. 452,416. In Canada J1m 10, 1942 v 7 Claims.(Cl. 2058) The invention relates to the drawing of metal, and moreparticularly to the colrl drawing of metallic tubes.

In the cold drawing of harder metals such as steel and nickel basealloys, it has been known to use softer'metals and unctuous materials tolubricate the die through which the metals were drawn. These lubricantsusually were applied to the metal stock prior to the drawing operation.When properly applied, a coating of lead has been found to besatisfactory sofar as its ability to prevent scratching, pick-up ofmetal on dies and mandrel, seizing, etc., was concerned,

but in some situations a lead or other soft metal coating cannot be usedor its use is not economical. For example, in drawing vvery thin walledtubes and in tube drawingrwhere the starting internal diameter andmandrel diameter are very nearly equal, a lead coating cannot be used onaccount of the relatively large minimum thickness of lead coatingrequired. Similarly, if it is necessary to give a piece of metal stock asingle draw, the cost of applying and removing a lead coating rendersits use uneconomical. Unctuous 'metal drawing over the use of tallow andoil lubricants has been brought about by covering the article to bedrawn with an adhesive such as sodium silicate, glue, shellac or thelike containing finely divided solids, e. .g., lamp black, lithoa methodof lubricating metals for a drawing operation which permits a greaternumber of passes and greater total reduction in area per application oflubricant and which also enables the drawing to be carried out at higherspeeds.

Other objects and advantages of the'present invention will becomeapparent from the following detailed description thereof. 1

Generallyspeaking, the lubricant of the present invention may becharacterized as a dual layer lubricant. .The first layer is a coatingof lubricating material applied to the surface 'or surfaces of themetallic shape that will contact the dies, mandrels, etc.,-during thedrawing operation. The second layer of lubricant is applied over thefirst layer just before the metal enters the die.

The lubricant which will be applied as the first layer is prepared bysuspending finely divided solid lubricant such as graphite or' lampblack and roughness producing powder such as lithopone in an adhesivevehicle such as shellac, cut

with alcohol. This first layer of lubricant is then pone, whiting androuge, but even with these 'im- I proved lubricantsthe speed of drawingwas slow, frequent recoating was necessary, and the number of passeswithout the necessity for annealing, pickling and recoating was low.

We have discovered a new lubricant and meth- 0d of drawing, particularlytube drawing,.which greatly increases the speed of draw and the numberof passes which the metal being drawn can withstand before requiring"annealing, as compared with prior art practices employing the best knownadhesive bonded solid powder type of lubricants.

It is an object of our invention to provide a lubricant that maybereadily applied to the metal stock prior to the drawing operation andreadily removed therefrom after drawing. It is another object of ourinvention to provide applied to the article to be drawn by dipping,spraying, brushing, etc. and is permitted to dry before the articleenters the die. The second layer is a dry powdered lubricant, e. g.,graphite,'powdered soap or preferably a mixtur of graphite and soapwhich is brought into contact with the article being drawn just beforeit enters the die. -Any acceptable wire drawing soap in powdered formcan be used in the present process. The roughness producing powder inthe first coating apparently drags a layer of the dry powdered lubricantthrough the die.

The percentage of solid lubricant and roughness producing agent in theadhesive vehicle can vary overa wide range. Two specific examples oflubricants which have given satisfactory results' ln service had thefollowing compositions, by volume:

Lubricant Na. 1 Lubricant No.2 Parztg Alcoh Alco Shellac... 10 Graphitel Lithopone 1 A screen analysis of the graphite and lithopone gave thefollowing results:

Mesh Percent Percent graphite lithopone On 20 6. 0 On 40 14. 2 On 50 5.6 On 60 1 On 80. 2. 5 43. 6 On 100. 23. 1 15. 4 On 140. 30. 3 0n200 i22.0 11.8 'lhrougli 200 22.0 3. 4

In one series of drawing operations employing a lubricant having theabove composition, stainless steel tubes having an outside diameter f 2%inches and a wall thickness of 0. 25 inch were coated inside and outsideby' dipping the tubes in the lubricant, draining and permitting thelubricating layer to dry before the drawing operation. These coatedtubes were then slipped over form of a second lubricating coating bythelithopone which gave the inner coating a distinct rough feel. Tubesprepared in this manner could be given twice as many passes at 3 to 6times the best drawing speed obtainable on the same kind and size oftubes coated with shellac and lithopone and additionally lubricated withoil at the die. Some stainless steel tubes, for example, were given areduction of about 50% in three passes using the lubricant of thepresent invention.

The following specific example will demonstrate the advantages of thepresent invention in the drawing of tubes made of an alloy containingabout 80% nickel, 14% chromium and 6% iron.

cium carbonate) and whiting. Instead of shellac, other adhesives of adrying nature may also be used with satisfactory results. Typical ofsuitable adhesives are varnish of nitrocellulose or cellulose acetatebase; synthetic resins, such as Bakelite, Vinylite, etc., in suitablesolvents; solutions of rubber or rubber products such as pliofilm, etc.

Although the present invention has been described in considerable detailin connection with certain specific embodiments, it will be understoodthat modifications and variations may be resorted to without departingfrom the scope of the invention as defined in the following claims.

We claim:

1. A metal tube prepared ,for cold drawing, having a coating of drawingcompound adhesively bonded to the surfaces of the tube which willcontact the die and mandrel during the drawing operation, said drawingcompound containing finely divided solid lubricant from the groupconsisting of graphite and lamp black and finely dividedroughness-producing material from 'the group consisting of lithopone,talc, soapstone, chalk and whiting, whereby the exposed surface of thecoating is rough; and solid lubricant from the group consisting of soapand graphite over the exposed rough surface of said coating.

2. A metal tube prepared for cold drawing, having a. coating of drawingcompound adhesively bonded to the surfaces that will contact the die andmandrel during the drawing operation, said drawing compound containingfinely divided solid Outside diameter 1 Lubri- No. of Outside Speed ofdraw diameter l thick- Percent reduction soup

turns 1 Inches. I Feet per minute.

The process of the present invention also is highly advantageous in thedrawing of age hardenable nickel-co'pper-aluminum alloy containingapproximately 66%Ni, 29% Cu and 2.75% Al as the following specificexamples will illustrate:

lubricant and finely divided roughness-producing material softer thanthe metal tube, whereby the exposed surface of the coating is rough; andsolid lubricant from the group consisting of soap and graphite appliedto the exposed rough surface of Lubricant No.

Wall thickness 1 Outside Outside sr diameter No. of Speed passes Percentreduction HHNb- N PPPP-"N QOOOQ ONNNN Inches. Feet per minute.

Drawn in steps of 2 passes each with 4 intermediate anneals and 5dopings.

Graphite is the preferred solid lubricant in the first layer althoughthe present invention contemplates the use of other equivalent powderedlubricants such as finely divided metal powders which may be used inconjunction with or as a substitute for graphite. For example, aluminumpowder alone and coniointly with graphite has given satisfactory resultsin practice. The preferred roughness producing agent is lithopone butother powdered materials of comparable hardness, particle shape andspecific gravity can be used instead'of lithopone. Suitable roughnesswhich comprises applying to the inner and outer surfaces of the tube adrawing compound containing finely divided solid lubricant from thegroup consisting of lamp black and graphite, and finely dividedroughness-producing material from the group consisting of lithopone,talc, soapstone, chalk and whiting, in an adhesive vehicle; drying saiddrawing compound to form on said inner and outer surfaces of the tube anadherent coating having an exposed rough surface; applying solidlubricant from the group consisting of graphite and soap over theexposed rough surface of said producing agents are talc, soapstone,chalk (cal-- adherent coating; and drawing the metal tube.

4. The method of drawing metal tubes made of alloys consistinglargely ofnickel and copper, which comprises applying to the inner and outersurfaces of the tube a drawing compound con-. taining finely dividedsolid lubricant from the group consisting of lamp black and graphite,and finely divided roughness producing material from the groupconsisting of lithopone, talc, soapstone, chalk and whiting, in anadhesive vehicle; drying said drawing compound to form on said inner andouter surfaces of thetube an adherent coating having an exposed roughsurface; applying solid lubricant from the group consisting of graphiteand soap over the exposed rough surface of said adherent coating; anddrawing the metal tube.

5. The method of drawing metal tubes which coating having an exposedrough surface apply-- ing solid lubricant from the group consisting ofgraphite and soap over the exposed rough surface of said adherentcoating; and drawing the metal tube.

8. The method of drawing metal tubes which so comprises applying to "thesurfaces of the tube that will contact the die and mandrel during theform on thesurfaces of said 'tube an adherent coating having an exposedrough surface; drawing said tubethrough a die; and supplying finely 10divided solid lubricant-from the group com sting of graphite and soap tothe coated surfaces of said tube as it enters the-die, whereby theexposed rough surfaces of said coating drag a quantity ofsaidlubricant'with themthrough the die.

7. The method of drawing metal tubes which comprises applying to thesurfaces of the tube that will contact the die and mandrel during thedrawing operation, a drawing compound containing finely divided solidlubricant and finely di- 20 vided roughness-producing material in anadhesive vehicle; drying said drawing compound ,to form on the surfacesof said tube an adherent coating having an exposed rough surface;drawing said tube vthrougna die; and supplying finely 25 divided solidlubricant tothecoated surfaces of said tube as it enters thedie, wherebythe exposed rough surfaces of said coating drag a quantity of, saidlubricant with them through the die. JOHN L. GOHEEN, Jn,

' CHARLES F. CATLIN, Jn,

